This invention relates to the preparation of a magnesium halide support for catalysts. More specifically it relates to activating the surface of a magnesium halide support for the titanium halide component of coordinate complex catalysts for the polymerization of alpha-olefins.
There are three modes for the polymerization of olefins such as ethylene, propylene, butylene, butadiene, and other olefins containing up to twelve carbon atoms. The three general modes for polymerization of olefins employ either free radical, ionic, or coordinate complex catalysts. The coordinate complex catalysts are often termed Ziegler-Natta catalysts in honor of the two scientists who made major contributions to their development. Coordinate complex catalysts have two components, one based on organometallic compounds of Groups I, II, and III, often of aluminum, the other based on a transition metal salt such as titanium halide.
It has been found advantageous to support the titanium halide component on a magnesium halide or manganese halide support, as disclosed in U.S. Pat. No. 3,642,746 granted to Kashiwa et al. Further, it has been disclosed that the magnesium halide or manganese halide supports can be activated by being prepared with a high surface area by precipitation or evaporation from organic solvents, by milling the surface, or by activation with an organoaluminum compound. Of these methods U.S. Pat. No. 4,156,063 granted to Giannini et al. discloses that milling is preferred.
A criterion for the activation of magnesium halide or manganese halide supports is provided in U.S. Pat. No. 3,789,036 granted to Longi et al. In that patent the disclosure is made that milling to the point that the sharp X-ray diffraction line at d=2.56 A (now known to be 2.57 A) for dehydrated samples of magnesium halide is broadened to a diffuse halo, indicates the proper level of activation.
U.S. Pat. No. 4,149,990 granted to Giannini et al. discloses that for rhombohedral magnesium chloride the X-ray diffraction line at d=2.56 A (sic) should be broadened to disappearance and for hexagonal magnesium chloride the X-ray diffraction line at d=2.75 A should be broadened to disappearance and for magnesium bromide the X-ray line at d=2.93 A should form a halo.
U.S. Pat. No. 4,064,334 granted to Kuroda et al. discloses that copulverizing magnesium halide with various organoaluminum compounds and titanium compounds and mixtures thereof provides a superior support for the coordinate complex catalysts for the polymerization and copolymerization of olefins.
U.S. Pat. No. 3,991,260 granted to Matsuura et al. discloses a process for polymerization of ethylene by a catalyst supported on a hydrous magnesium halide copulverized with various additives.
The methods disclosed above and many other similar published ones all involve copulverization or milling of the magnesium halide with one or more complex chemicals. It would be highly advantageous to be able to produce the support with an activated surface without the necessity of employing complex chemical additives when milling a support material.
It is an object of the present invention to prepare an anhydrous magnesium halide or manganese halide support for catalyst components containing titanium halide. It is a further object of this invention to provide an anhydrous magnesium halide or manganese halide support for catalysts with an activated surface. Still another object of the present invention is to provide an activated, anhydrous magnesium halide or manganese halide support for catalyst components containing titanium halide without the necessity of copulverization with organometallic additives. Other objects of the invention will be evident to those skilled in the art of catalytic polymerization from the description and Examples below.